Problems implementing po/mo file

I edited the .pot file in PoEdit which generated the .mo file. I moved both into the languages folder naming them buddypress-en_US. The codex instructions said to upload the .po file, so I assumed that means I’d have to rename the extension from .pot to .po, so I did that.

The pot and the po files are “working” files, they are not needed on the server.
The pot contains all translatable strings
The po contains the translatable strings AND the translation
The difference is also in both file header. The pot has a blank summary, the po’s summary has some configuration informations. (path, author name, plural settings and DOM info)